Just that he can achieve vehicular control. Simply blasting upwards is probably the easiest thing to do, but if you're wanting to survive the flight, there are a few other considerations. Now that they're doing powered landings, fine vehicular control is especially important. Hovering in place is probably the easiest part of that problem; controlling a descent is going to be a bit more difficult (as their boosted hop demonstrated).

Just from looking at their videos, none of their previous hovering techniques were really satisfactory. If you can't do a really stable hover, then you definitely won't be able to control a dynamic descent. However, that last hover test (before they wrecked the vehicle) just NAILED it -- It looked as stable as the DC-X or the Japanese RTV -- so I don't expect that they'll be messing around with hovering much longer. I think it's safe to now predict that with each new vehicle they build, they'll be able to quickly hover-test it (just to be sure), before moving on to higher and higher boosted hops. Their progress in the next couple of months should be rapid, regulation-permitting, and I look forward to watching it unfold every Sunday! While I think it's quite unlikely that they'll snatch the prize away from Burt, I think they've got a decent chance of going supersonic with a subscale vehicle before the end of the summer.

Cheers,

Nathan